98hd can you post a pic of the rusted areas?
if its just short lengths, you can bend replacement sheetmetal to match fairly easily in a vice with a body hammer and piece it in.
if longer, you need a sheetmetal break and then slice it every inch to let it curve. blend with hammer.
if just small holes, you can put a piece of copper behind the hole and use a mig welder to "fill" the hole by deposting metal. the molten metal will not stick to the copper., then grind. the back side will be nice and smooth cause its formed by the copper. I have filled thousands of holes with this techinique, its like pouring molten steel into the hole. you cant even tell its been repaired once you get it done. works good on trunk lips cause they dont warp because of all the sharp bends. you can bend the copper to fit the curves etc and just fill away.